<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>伪类选择器</title>
</head>
<link rel="stylesheet" href="./3.css">
<body>
    <div class="container">
        <h1>h1:active</h1>
        <h2>h2:hover</h2>
        <input type="text" placeholder="输入框" autofocus>
        <input type="checkbox" id="option1" checked>
        <label for="option1">选项1</label>
        <input type="checkbox" id="option2" >
        <label for="option2">选项2</label>
       <ul>
        <li>列表1</li>
        <li>列表2</li>
        <li>列表3</li>
        <li>列表4</li>
       </ul>


    </div>
</body>
</html>